黄河三角洲飞雁滩动力特征与地形剖面塑造

Dynamics Characteristics and Topographic Profiles Shaping Process of Feiyantan at the Yellow River Delta

飞雁滩是1964年1月至1976年5月黄河尾闾由刁口流路入海形成的黄河亚三角洲。自1976年黄河改走清水沟入海后,飞雁滩岸滩发生强烈侵蚀后退。以20世纪70年代开始的地形固定断面观测资料、2004年4月现场水文泥沙及沉积物取样资料为基础,地形剖面后退距离作为统计参数,并根据实测资料计算了潮流和波浪底摩阻流速的横向分布,分布和沉积物结构方面解释了飞雁滩典型剖面的变化特征。30a来飞雁滩岸滩地形剖面经历了"快速后退侵蚀-慢速调整-波动触发"的变化过程,这也正是其三角洲前缘侵蚀逐渐消失过程。沉积物抗冲性强弱是剖面蚀退速度变化的主要原因,水动力条件的变化改变了不同阶段的地形剖面最大蚀退量水深范围与闭合深度。风暴潮仍是今后海滩地形剖面演变的触发动力。

Feiyantan beach is a sub Yellow River delta, which is formed from Jan 1964 to May 1976, when the Yellow River entered sea via Diaokou River. Since the terminal reach changed to Qingshuigou channel in 1976, Feiyantan beach is corroded strongly. There are regular topographic profiles for observing in the 1970＇s. Field works were carded out to measure hydrology and suspended sediment and fetch the sediment of seashore and sediment core in April, 2004. Regarding backwards distance as topographical statistical parameter, and according to field survey materials, the distribution of tidal and bottom wave friction velocity is calculated. The paper explains evolution characteristics of profile from dynamical force and sediment characteristics. The profile of Feiyantan beach experienced the process of ＂fast erosion - slow eroding modulation - fluctuate triggering change＂ in recent 30 years, which is also gradually disappearing the process of the front of delta. The intensity of the erosion resistance of the sediment is the main reason that the erosion speed changes. The water depth range of maximum recession backward distance and depth between erosion and progradation became shallow because hydrodynamic force changed. It indicates that the storm tide is still the triggering force for the evolvement of seashore topographic profiles in the future.